The present invention relates generally to a fuel rail formed by a lost core process which is formed in one piece and includes attachment features for the attachment of fuel injectors to the fuel rail.
A fuel rail delivers fuel from the engine""s fuel tank system and into an internal combustion engine. For a V-type internal combustion engine, it is common to form the fuel rail from two main fuel tubes. The fuel tubes are commonly made of metal or plastic and are either molded or are stamped and welded. The fuel tubes are connected by a metal cross-over tube which conveys fuel from one tube to the other. O-rings are used to seal the connection. The fuel rail also includes a plurality of sockets. Fuel injectors are inserted into the sockets to supply fuel to the internal combustion engine. The fuel injectors are secured to the sockets of the fuel rail by stamped metal clamps.
A drawback to the prior art fuel rail is that additional materials are needed for assembly. A cross-over tube and o-rings are needed to attach the fuel tubes, and stamped metal clamps are needed to secure the fuel injectors to the fuel tubes. These additional materials are costly and require additional time for assembly.
Hence, there is a need in the art for an improved fuel rail formed by a lost core process which is formed in one piece and includes attachment features for attachment of fuel injectors.
The present invention relates generally to a fuel rail formed by a lost core process which is formed in one piece and includes attachment features for attachment of fuel injectors.
The fuel rail of the present invention is formed by a lost core process. A metal core is formed and then over-molded with plastic. The plastic over-molded metal core is immersed in a hot bath, typically of glycolitin oil. As the melting temperature of the metal core is less than the melting temperature of the plastic overmold, the metal core melts, leaving the plastic overmold fuel rail.
As the fuel rail is formed by a lost core process, attachment features can be easily formed for attachment of fuel injectors to the fuel rail. In a first embodiment, the fuel rail includes a plurality of cylindrical sockets including an enlarged annular rim. Each fuel injector has a snap fit connector including a pair of inclined portions separated by a gap. A flat surface is formed by the inclined portions. The diameter of the flat surface is slightly larger than the inner diameter of the annular rim. When a snap-fit connector of the fuel injector is inserted into a cylindrical socket of the fuel rail, the inclined portions are slightly pressed together, eliminating the gap and reducing the diameter of the flat surface and allowing the inclined portions to pass through the annular rim. Once the inclined portions pass through the annular rim, the gap reforms, securing the fuel injector to the fuel rail.
Alternatively, a plurality of internal threads are molded on the inner surface of the cylindrical socket of the fuel rail. Each fuel injector includes a plurality of corresponding external threads which are threaded into the internal threads of the socket, securing the fuel injector to the fuel rail.
In a third embodiment, a groove is molded into the inner surface of a cylindrical socket of the fuel rail. The external surface of each of the fuel injectors includes a corresponding notch. When the fuel injector is positioned in the socket of the fuel rail, the notch engages the groove, and the fuel injector is secured in the fuel rail by a twist and lock connection.
Accordingly, the present invention provides a fuel rail formed by a lost core process which is formed in one piece and includes attachment features for attachment of fuel injectors.